Re-reading evo this morning they report that the Birds
MCS they drove also had an optional £750 Hartge four-pipe exhaust on it, which improves sounds but doesn't generate more power as it uses standard cats which are the inhibitor. This suggests that if they dropped the cats then they could be looking at more than the dyno'd 212bhp.
The GGR Stage 2 seems to bypass the cats, meaning that 220bhp would sound like a possible figure.
For my money and of the two above and the
JCW kit, I am leaning in the direction of Hartge - TUV approved, very reputable tuner (woth £500 over GGR for my peace of mind) and nearly £2k saving over the
JCW kit. Even though you blow the TLC, I wouldn't imagine on savinbg £2k over two years with that scheme anyway.